Axial Flux Machine

Abstract

An axial flux machine is described. The machine has a stator comprising a stator housing enclosing a plurality of stator bars disposed circumferentially at intervals around an axis of the machine, and a rotor comprising a set of permanent magnets and mounted for rotation about the axis of the machine. The rotor is spaced apart from the stator along the axis of the machine to define a gap between the stator and rotor and in which magnetic flux in the machine is generally in an axial direction. The machine also comprises a hub assembly comprising a rotating hub and a mount separated by a bearing to permit the hub to rotate relative to the mount, the rotating hub comprising a hub flange and the mount comprising a mount flange, each of the flanges being spaced axially apart from one another. The machine further comprises a bulkhead for mounting the hub assembly and stator, wherein the bulkhead is mounted to the mount flange of the hub assembly and the stator housing is mounted to the bulkhead. The rotor comprises first and second rotors disposed either side of the stator, the first rotor being mounted to the hub flange and the second rotor being mounted only to the first rotor, the first and second rotors together forming a U-shaped rotor extending across and either side of the stator and being rotatable relative to the stator about the axis of the machine.

Description

FIELD OF THE INVENTION[0001]The present invention relates to axial flux machines.BACKGROUND OF THE INVENTION[0002]In the present invention, we are concerned with axial flux permanent magnet machines. Broadly speaking these have disc- or ring-shaped rotor and stator structures arranged about an axis. Typically the stator comprises a set of coils each parallel to the axis and the rotor bears a set of permanent magnets and is mounted on a bearing so that it can rotate about the axis driven by fields from the stator coils. FIG. 1a shows the general configuration of an axial flux machine of the present invention with a pair of rotors R1, R2 to either side of a stator S—although a simple structure of the present invention could omit one of the rotors. As can be seen there is an air gap G between a rotor and a stator and in an axial flux machine the direction of flux through the air gap is substantially axial.[0003]There are various configurations of axial flux permanent magnet machine dep...

AI Technical Summary

Benefits of technology

[0022]Such an arrangement, as well as providing a labyrinth seal between the stator and rotor, also provides additional stiffness to the structure of the rotor.

[0023]Alternatively to the above, the second rotor may be mounted only to the first rotor along an internal portion located radially inward from its outer axial rim. In this case, the first and second rotors together form a U-shaped rotor extendin

Problems solved by technology

As can be appreciated, dispensing with the stator yoke provides a substantial saving in weight and iron losses, but one drawback is loss of rigid structure in which a bearing can be mounted to support rotors.

However radial ribs are costly to machine and add length to the axial dimension of a motor.

Iron based rotors are typically used and the mass of these increase significantly with

Images